September 21, 20241 yr I have a fat bike with a motor in the rear wheel (Bafang 250W). The control unit (voltage 36V, max. current 17A, rated current 8A) has a connector for both the PAS sensor, which is currently active and functional (the motor only engages when the pedals are turned), and a connector for a thumb throttle, which is connected via a cable from the unit to the handlebars, ending there in a 3-pin SM female connector. I bought a brand new thumb throttle, compatible with my motor and having a 3-pin SM male connector, but after connecting the connectors, the (thumb throttle) device does not work – pressing the throttle does not engage the motor or cause any other response. Does anyone know what needs to be adjusted or configured to make the thumb throttle work (to engage the motor)?
September 21, 20241 yr If you pedal will the motor respond to the throttle? if built for the eu/uk market the controller may be limited to some degree as to what throttle 'service' it can provide if any. If a manual for the bike detailing how to configure its settings isnt available you may find a generic manual online searching for any 'manual pdf' documents related to your LCD display unit (if fitted) as this would be your interface to the controller configuration. This could detail 'turning on/off' throttle control??
September 21, 20241 yr Author If you pedal will the motor respond to the throttle? I'm not sure if I asked correctly. I installed the thumb throttle so that I wouldn't have to pedal at all, but rather that the device would engage the motor by pressing the throttle without the need to pedal. If a manual for the bike detailing how to configure its settings isnt available you may find a generic manual online searching for any 'manual pdf' documents related to your LCD display unit (if fitted) as this would be your interface to the controller configuration. This could detail 'turning on/off' throttle control?? I have a manual for my LCD display (Nokee-U - https://bit.ly/3XPNqHS), but the thumb throttle is not mentioned in the manual at all.
September 21, 20241 yr Larkbox asked the question because for compliance reasons the display/controller should be set up so you have to peddle first to activate the throttle. So if you peddle, does motor respond to the throttle? Edited September 21, 20241 yr by AGS
September 21, 20241 yr Author So if you peddle, does motor respond to the throttle? No. The thumb throttle device does not respond in any situation – whether the bike is stationary or the motor is already running and I'm pedaling. The motor only activates in response to pedaling, i.e., through the PAS sensor.
September 21, 20241 yr Controller labels often have an indication along the lines of "THROTTLE: 1-4.1v" or similar which would confirm it should work. Although an absence is proof of nothing.. can you confirm wire colours red and black ... are connected correctly? And are you connecting directly to the controller or via a wiring loom or connecting cable? you can also check the throttle supplying it 5v and checking the voltage on the output wire
September 21, 20241 yr I have a fat bike with a motor in the rear wheel (Bafang 250W). The control unit (voltage 36V, max. current 17A, rated current 8A) has a connector for both the PAS sensor, which is currently active and functional (the motor only engages when the pedals are turned), and a connector for a thumb throttle, which is connected via a cable from the unit to the handlebars, ending there in a 3-pin SM female connector. I bought a brand new thumb throttle, compatible with my motor and having a 3-pin SM male connector, but after connecting the connectors, the (thumb throttle) device does not work – pressing the throttle does not engage the motor or cause any other response. Does anyone know what needs to be adjusted or configured to make the thumb throttle work (to engage the motor)? Just because it has the same connector, it doesn't mean it's wired the same way. Does the throttle listing show the pinouts?
September 22, 20241 yr Author Just because it has the same connector, it doesn't mean it's wired the same way. Does the throttle listing show the pinouts? No information about pinouts. However, here are the pictures of my controller and the purchased thumb throttle (https://amzn.to/4gxqCE6). The controller diagram was provided by the bike manufacturer. Hopefully, this might help with remote diagnosis of the issue...
September 22, 20241 yr No information about pinouts. However, here are the pictures of my controller and the purchased thumb throttle (https://amzn.to/4gxqCE6). The controller diagram was provided by the bike manufacturer. Hopefully, this might help with remote diagnosis of the issue... If you have those connectors, you can see the colours of the wires. Does it go red to red, black to black and white to green?
September 22, 20241 yr Author If you have those connectors, you can see the colours of the wires. Does it go red to red, black to black and white to green? Bingo! The problem was indeed with the incorrect wire order. I swapped the wires into the correct order, and everything is working now. Thank you for the helpful comment that led me to the solution!
September 22, 20241 yr I'm not sure if I asked correctly. I installed the thumb throttle so that I wouldn't have to pedal at all, but rather that the device would engage the motor by pressing the throttle without the need to pedal. Are you using the bike in the UK ?
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